the.com/problem of universals

means It's the philosophical puzzle of whether general properties or categories (like 'redness' or 'treeness') exist independently and really, or whether only particular individual things exist and 'universals' are just labels we apply to them.

from The term descends from medieval scholastic philosophy, where 'universal' traces to Latin universalis, 'of the whole,' from universus. Debate flared over Boethius's Latin translations of Porphyry, who had asked — without answering — whether genera and species exist in reality or only in the mind. Medieval thinkers split into camps: realists (universals exist, often in a Platonic or moderate form), nominalists (only names exist, 'universal' is just a word), and conceptualists in between. The dispute became one of the defining arguments of medieval philosophy, and the phrase 'problem of universals' stuck as its label.